Lobed rotary cutting blade

ABSTRACT

A MULTI-LOBED CUTTING BLADE HAVING A PLANE MEMBER ADAPTED FOR MOUNTING TO A ROTARY DRIVE SHAFT AT RIGHT ANGLES TO THE PLANE MEMBER. THE PLANE MEMBER INCLUDES THREE OR MORE LOBES SACED APART RELATIVE TO ONEANOTHER AND A PLURALITY OF ABBREVIATED SECTORS SPACED APART RELATIVE TO ONE ANOTHER WITH AN ABBREVIATED SECTOR INTERMEDIATE TWO LOBES SUCH THAT THE OUTER PERIPHERAL EDGE OF EACH LOBE EXTENDS TO THE OUTER PERIPHERAL EDGE OF AN ABBREVIATED SECTOR. EACH OF SAID LOBES AND ABBREVIATED SECTORS CARRIES A CUTTING EDGE SURFACE ABOUT ITS&#39;&#39; OUTER PERIPHERY.

Unlted States Patent 1191 1 1 3,831,484 Gibb Aug. 27, 1974 LOBED ROTARYCUTTING BLADE I [76] Inventor: David T. Gibb, Rt. No. 2, primay Schra"Ellensburg wash 98926 Attorney, Agent, or Firm-Schatzel & Hamrick 22Filed: Dec. 13, 1971 i [21] App. No.: 207,416 [57 ABSTRACT 52 us. on83/847, 83/676, 125/5, A multi-lobed cutting blade having a plane memberY 51 1 144 21 adapted for mounting to a rotary drive shaft at right 51Int. Cl B27b 33/08 angles to the Plane member- The Plane member [58]Field f s h 143/133 M, 133 R; 144/233 cludes three or more lobes spacedapart relative to 144 239 213; 125 5; 51 1 3; 33 335 347 one another anda plurality of abbreviated sectors 848, 854, 855, 663, 676 spaced apartrelative to one another with an abbreviated sector intermediate twolobes such that the outer [56] References Cit d peripheral edge of eachlobe extends to the outer pe- UNITED STATES PATENTS ripheral edge of anabbreviated sector. Each of said 2 239 317 4/1941 Gbb 143/133 M lobesand abbreviated sectors carries a cutting edge l c0 a 2,822,648 2/1958Metzger et al. 143 133 B x surface about outer per'phery' FOREIGNPATENTS OR APPLICATIONS 3 C|aims,'4 Drawing Figures 172,082 6/1906Germany 143/133 M LOBED ROTARY CUTTING BLADE BACKGROUND OF THE INVENTIONThe present invention relates to improvements in rotary cutting bladesand more specifically to blades capable of cutting longitudinally and/orlaterally.

The building industry is continuously in search of improved methods andtools to aid in the construction of building structures. Power saws,such as table saws, band saws, radial arm saws, jig saws and portablecircular saws, are commonly used tools. The utility of such saws isdependent in large measure upon the design and structure of the sawblades. Variou blade structures have been proposed for performingvarious tasks. Various uses include making circular cuts in materials ofwood, plastics, etc.; cutting bee-box boards; cutting hand holds in beeboxes; making starts for rotary or jigsaw blades for window cut-outs inwalls, etc.; and abrasive blades, e.g. fibre blades, for cutting andgrinding off high spots of brick, stone, concrete, etc. Heretofore therehave been proposed rotary saw blades of the wobble type with teethspaced at varying distances from the axis of rotation, which are adaptedfor the formation of tongues and grooves in boards and other materisla.Wobble saws, however, are primarily adapted only for making cuts oflimited sizes and shapes for which they are specifically designed andare limited as to their use for making ordinary saw cuts. Wobble bladesof such design are depicted in US. Pat. No. 2,756,787 granted to HenrySies and Austrian Patent No. 197,069. The prior art includes othernoncircular shaped blades.

The present inventor, as disclosed in US. Pat. No. 2,239,317, hasheretofore disclosed and described an ellipsoidal planar blade adaptedfor cutting laterally and longitudinally. The present invention hasproven to provide substantially improved operation over the ellipsoidalblade in making lateral and/or longitudinal cuts and in structuraldurability.

SUMMARY OF THE PRESENT INVENTION The present invention provides animproved saw blade for rotary saws. The blades are adapted to cutmaterials longitudinally and/or laterally to establish a plurality ofdifferent designs upon the demand of the operator. The capability of thepresent invention represents an advance over ordinary circular sawblades, ellipsoidal and other proposed non-circular blades. Relative toother non-circular blades, blades of the present invention provide forsmoother rotation of the blade and faster, smoother cutting of thematerial; allows for better cleaning of the blade teeth; and for a morestable, stronger blade structure, which enhances safety to the operator.The required power to drive blades of the present structure forperforming a given task is less than that of ellipsoidal blades.

The present invention provides for multi-lobed blades. As hereinafterutilized, the term sector shall be defined to include an angular segmentof the blade; the term lobe will be defined to include a sector having aconvex rounded projection of uniform radius relative to the axis ofrotation of the blade; and the term an abbreviated sector shall bedefined to include a sector of substantially triangular phase or asector with a concave rounded edge such that any two points along theperipheral edge contour of a given sector are equal distance from saidaxis of rotation where one of said points is spaced a given distancealong the periphery from the leading edge and the other point is placedan equal given distance along the peripheral edge from the trailing edgeof each of said lobes.

Exemplary embodiments of blades of the present invention include aunitary plane member having an axis of rotation and structured toinclude three or more lobes with a like number of abbreviated sectorsextending radially from said axis of rotation. The lobes and abbreviatedsectors are positioned intermediate to one another such that each lobeis intermediate a pair of abbreviated sectors and each abbreviatedsector is intermediate a pair of lobes. Each of said lobes andabbreviated sectors carries a cutting peripheral edge, e.g. a pluralityof teeth.

The general efficiency of the present blade; the smoother rotation ofthe blade; the faster, smoother cutting and better cleaning realized bythe present structure are believed to result from the structuralimprovements of the present blade. The present structure provides for adistribution of teeth which takes into account the inverse relationshipof rotary speed and power of a lever such as a rotating saw blade, andthe effect of this inverse relationship on the cutting action of anon-circular rotating blade. The present structure permits teeth to bepositioned at different radii relative to the axis of rotation, therebypermitting lateral and/or longitudinal cutting of a material. It furtherprovides for relative even and uniform spacing of the greatest number ofthe teeth at the greatest radius, in turn providing high efficiency.This result is believed to emanate from the fact that the coefficient ofpower is at its smallest value at the maximum radius point and thecoefficient of speed the largest relative to all the radii of the blade.Relative to an ellipsoidal blade, the present structure permits theincorporation of a greater number of teeth positioned at shorter radiiwith the teeth being closer together about the periphery of the blade.At the same time, the present structure provides for a greater number ofteeth at the maximum radii, whereas an ellipsoidal blade is limited totwo teeth at the maximum radii and four teeth at each lesser radii.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. '1 is a side view of a rotary sawblade incorporating the teachings of the present invention;

FIG. 2 is a perspective view of the blade of FIG. I mounted on a driveshaft of a table saw;

FIG. 3 is a view of an alternate embodiment of a blade of the invention;and

FIG. 4 is a perspective view of an alternative blade of the presentinvention with an abrasive cutting edge.

DESCRIPTION OF PREFERRED EMBODIMENT Referring to the drawings, FIG. 1depicts a saw blade, referred to by the general reference character 1and incorporating the teachings of the present invention. The blade 1comprises a multi-lobed planar member 3 shaped with three sectors 5, 7,and 9 having a convex or lobed outer pheripheral contour and threesectors 11, 13, and 15, having a concave parabolic outer peripheralcontour. The sectors 5, 7, and 9 are hereinafter referred to as lobes,and the sectors 11, 13, and 15 are hereinafter referred to asabbreviated sectors. The lobes 5, 7, and 9 and the abbreviated sectors 1l, 13 and 15 are structured such that intermediate adjacent lobes is anabbreviated sector and intermediate adjacent abbreviated sectors is alobe such that the leading edge of a lobe coincides with the trailingedge of an abbreviated sector. The lobes 5, 7, 9 and sectors 11,13, andall extend radially from an axis 17. Each lobe and abbreviated sectorcarries a plurality of standard teeth 19 disposed along theouterperipheral edge to establish a cutting edge. The teeth 19 areshaped such that the blade cuts as it is rotationally driven inaclockwise direction. The member 3 carries an aperture 21 about the axis17 so as to permit the blade 1 to be mounted to a rotating drive shaftas commonly existent on circular saw table saws, radial saws, and soforth. The lobes 5, 7, and 9 each comprise an arc of a radius R from thetip of the teeth 19 and a chord of distance D. Each lobe 5, 7, and 9 hasan angle of 60 betweenthe leading and trailing edge. Accordingly, aboutthe maximum radius R there are a plurality of teeth at each lobe withthe total number of teeth about the maximum radius multiplied by thenumber oflobes, which in the embodiment 1 is three.

The abbreviated sectors 11, 13, and 15 each have a chord of the distanceD and an angle of 60 between the leading and trailing edge. Theabbreviated sectors 11, 13, and 15 each have a maximum distance R fromthe axis 17 at the point at which their respective peripheral edgesconverge with the peripheral edge of the lobes 5, 7, and 9. Accordingly,the leading edge of the lobes 5, 7, and 9 coincide with the trailingedge of the abbreviated sectors 11, 13, and 15, respectively. Thetrailing edges of the convex-shaped lobes 5, 7, and 9 coincide with theleading edges of the sectors 15-, 1-1, and 13, respectively. Each of thesectors 1l,,13,.and 15 has a minimum distal spacing X from the axis 17coin? ciding with the center line 30 from the leading edge and trailingedge of the respective lobe. Thus, at the minimum radius X, the blade 1has three teeth, e.g. one

per sector 11, 13 and 15. At every radius greater than X and less thanR, as illustrated by the circle of radius y, the blade has a maximum ofsix teeth, i.e. two per sector 11, 13, and 15.

FIG. 2 illustrates the blade 1 as mounted on a conventional table saw 22having a base 23 and a planed smooth and flat top 25. The blade 1 ismounted on a drive shaft 27 driven by a drive motor 29. A stabilizerwasher 30 and nut 31 secure the blade to the shaft 27. If desired, afence member 32 may be positioned on the top 25 to aid in guiding theworkas itis fed to the saw blade 1. As illustrated, a throat plate 33 isremoved to illustrate the blade 1 mounted inplace.

In operation, an operator guides the work piece, e.g., piece of wood,metal or masonry, over the table top 25 laterally and/or longitudinallyrelative to the plane of the blade 1 so as to cut the desired design.The work piece may be guided longitudinally and/or laterally relative tothe plane of the blade.

FIG. 3 depicts an alternative embodiment of a saw blade, referred to bythe general reference character 51, and incorporating the teachings ofthe present invention. The blade 51 comprises a planar member 53 shapedwith four lobes 55, 57, 59 and 61 and four. abbreviated sectors 63, 65,67 and69. The lobes 55, .57,

59, 61 and the sectors 63, 65, 67 and 69 all extend radially from anaxis 71. Each lobe and sector carries a plurality of standard teeth 73disposed along the outer peripheral edge. The member 53 carriesanaperture 75 about the axis 71 so as to permit the blade 51 to bemounted to a rotating drive shaft. The lobes 55, 57,59 and 61 eachcomprise an arc ofa radius R from the tip of the teeth 73 and a chord ofadistance D; Each lobe 55, 57, 59 and 61 has an angle of 45 between itsleading and trailing edge.

The abbreviated sectors 63,65, 67, and 69 each have a chord distance Dand an angle of 45 between its leading and trailing edge. The sectors63, 65, 67, and 69 each have a maximum distance R from the axis 71 atthe point at which their respective peripheral edges converge with theperipheral edge of the lobes 55, 57, 59, and 61 and a minimum-distance Xfrom the axis 71 at the center line 22-% from the leading edge andtrailing edge of the respective sector. Accordingly, the leading edge ofthe lobes 55, 57, 59, and 61 coincide with the trailing edge ofthe'sectors 63,65, 67,.and 69, respectively. The trailing edge of thelobes.55, S7, 59, and 61 coincide with the leading edges of the sectors65,67, 69, and 63, respectively. Thus, at the minimum radius X, theblade 51 has four teeth, i.e. one per sector 63, 65,67, and 69. At everyradius greater than X and less than R, the blade has a maximum of eightteeth, i.e. two per sector, 63, 65, 67 and 69.

FIG. 4 illustrates an embodiment of a blade of the present invention,referred to by the general reference character 80, adapted for cuttingor grinding masonry products, e.g. stone, concrete, etc. The-blade maybe comprised ofa fibre material with-an abrasive peripheral cuttingedge. The blade 80 comprises four lobes 82, 84, 86 and 88, and fourabbreviated sectors 90, 92, 94 and 96' similar to the balde 51of FIG. 3.The blade 80 includes a central aperture coaxial with an axis 71 formounting to a power source. The cutting edge of the blade is comprisedof an abrasive material98. In operation, the blade 80 may be mounted ona power source individually, or with a gang of similar multi-lobedblades with an abrasive cutting edge. in an exemplary application, in agang the blades may be utilized to remove high spots of the masonry,e.g. a concrete surface.

I claim:

1. A rotary cutting blade, comprising a planar disc member adapted formounting about its axis of rotation to a rotary drive shaft and at rightangles to said drive shaft, the planar member including at least threelobe sectors of similar shape and dimensions and at least threeabbreviated sectors of similar shape and dimensions, each of said lobesectors having a leading edge and atrailing edge with the leading edgeofeach lobe common to the trailing edge of one of said abbreviatedsectors and the trailing edge of each lobe common to the leading edge ofone of said abbreviated sectors, the abbreviated sectors having auniform outer peripheral edge contour relative to said axis of rotationin which any two points along the peripheral edge of a given sector areof equal distance from said axis of rotation where one of said points isspaced a given distance along the periphery from the leading edge andthe other point is spaced an equal given distance along the peripheraledge from the trailing edge of the abbreviated sector, the outerperipheral edge contour of each of said lobe sectors and of each .ofsaid abbreviated sectors carrying a plurality of saw-teeth which teethare substantially evenly spaced relative to one another intermediate theleading edge and trailing edge of each of said lobe sectors and eachofsaid abbreviated sectors.

of the abbreviated sectors has a uniform concave parabolic peripheraledge contour relative to the axis of rotation of the blade.

